Final answer:
Charged particles like protons and beta particles (electrons) can be deflected by a magnetic field.
Step-by-step explanation:
In a magnetic field, particles can be deflected based on their electrical charge. When a charged particle moves through a magnetic field, it experiences a force perpendicular to both the direction of motion and the magnetic field. This force causes the particle to change direction. Positively charged particles, such as protons and positrons, will be deflected in one direction, while negatively charged particles, such as beta particles (electrons), will be deflected in the opposite direction.